Software engineering deals with the development of software and different types of web applications. Due to changes in the customer requirements, product modifications have to be done in the web application so that an organization can interact with more customers. In order to validate the modifications, regression testing has to be performed again and again. The test cases of the modified versions have to be re-generated and testing has to be performed for each module. This process involves maximum time and effort for the generation of test cases. In this paper, variable and constraints have been reused from the previous version of the web application. These constraints and variable that has been reused provides less effort and time for the modification of test cases. The test cases can be generated only for the modifications on the basis of reusable constraints and variables.